Yes, you’ve seen this movie before. And yes, even with 540 horsepower, to some a Mustang is not, strictly speaking, a sports car. A sports car, by the classic British definition, is one that can, in a pinch, be raced. But times change, and even our resident hotspur Brit, Mr. Gillies, thinks this is talk that predates his birth.
http://www.caranddriver.com/reviews/comparisons/09q4/2010_chevy_corvette_grand_sport_vs._2010_ford_mustang_shelby_gt500_-comparison_tests